by Elizabeth Weise, USA TODAY

Genetic tests have found ground horse meat in beef in Ireland, Britain, Germany, Italy, Poland and the Czech Republic. On Friday Taco Bell outlets in Britain found traces of the meat in what was supposed to be 100% beef. The company has removed all beef products from its menu in the United Kingdom.

There is no link between Taco Bell suppliers in Europe and the United States, the company said.

How the horse meat entered the European food supply is unknown.

The United States imports no beef from the European countries that found horse meat labeled as beef, Dept. of Agriculture officials said. "For imported products, (the U.S.) conducts port-of-entry re-inspections of all products offered for import into the United States, which provides evidence of how the foreign country's inspection system is performing," said Catherine Cochran with the Department of Agriculture's Food Safety Inspection Service (FSIS.) In addition, "FSIS conducts on-site food regulatory system audits at least once every three years in every country that exports meat, poultry, or egg products to our country."

Horse meat cannot be sold for human consumption in the United States, Cochran added. "There are currently no establishments in the United States that slaughter horses, and FSIS does not allow imports of horse meat from other countries for human consumption."

Furthermore, it's unlikely that horse meat disguised at beef or pork could make its way into the U.S. meat supply because "the meat and poultry inspection process in the U.S. puts FSIS inspectors carrying out our mandatory inspection requirements in U.S. plants every day they operate," she said.

Neither USDA nor FDA food inspections require genetic testing of meat to insure that it's from a particular animal, but any food so mislabeled would be grounds for food fraud allegations.

There's nothing intrinsically dangerous about eating horse meat. The lean meat is popular and heavily consumed in much of the world, especially Europe and China. But the initial danger is not the problem, said Bill Marler, a food safety lawyer in Seattle. "It's not so much a food safety issue, it's a food fraud issue. Obviously if someone's willing to fraudulently sell you horse meat and tell you it's beef, you have to question their interest in food safety as well."

Many animal rights groups have argued that horse meat shouldn't be sold for human consumption anywhere because horses are not raised under conditions that insure that their meat is safe to eat. Horses are work or race animals and they are often given drugs that make their flesh unsuitable for human consumption. Richard Raymond, former undersecretary for Food Safety at USDA, said there have been questions about butazolidin(called 'bute') a drug used to treat lameness and arthritis in horses, especially in race horses.

Horse meat hasn't always been illegal in the United State. Up until 2005 FSIS regularly inspected horse slaughter plants along with all other types of meat production facilities. Animal rights activists made a major push to stop the sale of horse meat and Congress added an amendment to the Agricultural Appropriations Act taking away funding for the inspection of horses being transported to slaughter.

FSIS then made horse inspection a fee-for-service inspection, just as bison still is. Congress went back and rewrote the law saying no money could be spent at "any inspection of horse slaughter," said Raymond, who at USDA at the time. By 2007 the last three American facilities that slaughtered horses for human consumption were shut down, according to a petition filed with USDA by the Humane Society in 2012.

Today American horses are still slaughtered for food, it just takes place in Mexico and Canada rather than on U.S. soil. The Government Accountability Office found that in 2010 more than 137,000 U.S. horses were sent to Mexico and Canada each year to be slaughtered. That's about as many were slaughtered in the United States before the ban went into effect in 2007, GAO said.

The recession and this year's drought, which drove up feed prices, has been very hard on horse owners. Many horses are neglected or abandoned by owners who can no longer afford food for them.

In fact, most of the horse meat in those two countries, which is sold to Europe, comes from horses raised in the United States. Canada is the largest exporter of horsemeat to Europe, according to the Humane Society of Canada, which is working to ban the practice there.

Two companies are currently trying to open horse slaughter plants in the United States, on in Missouri and one in New Mexico. USDA is reviewing their applications.

It's "doubtful" any dangerous pathogens were in the horse meat Europeans have inadvertently eaten, said Doug Powell, a professor of food safety at Kansas State University in Manhattan, Kan.

"It has been found in meals and products that are highly processed-the bad bugs would be cooked away." It's the public's trust that's been broken "and since almost all food safety at retail is faith-based, the faith has been violated."